Pulsed Optical Pumping as a Tool for the Determination of Population Mechanisms of Excited States in a Low-Pressure Mercury Discharge

Experiments are described in which a low-pressure mercury discharge is irradiated with a dye-laser pulse tuned resonant to one of the 6 3P-7 3S1 mercury transitions. The effects of this optical pumping process are monitored via fluorescence on many mercury transitions. The sign and time behavior of each fluorescence signal are different, and are determined by one or more of the following processes: a) radiative decay of the 7 3S1 level; b) a change in electron-impact excitation rate from the ground state induced by the optogal-vanic effect (OGE). This OGE results from the population redistribution in the 6 3P levels after radiative decay of the 7 3S1 level; c) a change in electron-impact excitation rate from the 6 3P levels; and d) a change in 6 3P-6 3P collisional excitation rate. It is demonstrated that the signal and time behavior of the fluorescence signals induced by the pulsed optical pumping process can be used to determine the population mechanism(s) of excited states qualitatively.